1. Field of the Invention
The present invention is directed to new diisocyanates and to a process for their preparation from diisocyanates and trialkylsilyl cyanides.
2. Description of the Prior Art
The new diisocyanates according to the invention advantageously differ from the most structurally similar diisocyanates according to German Offenlegungsschrift No. 2,329,300 by the fact that they do not undergo any further reactions accompanied either by splitting off of physiologically harmful decomposition products (in the case of the diisocyanates according to German Offenlegungsschrift No. 2,329,300 there is the possibility of decomposition with reversion to the diisocyanate used as starting material and hydrocyanic acid) or by chemical addition of the diisocyanates to mixtures of di- and triisocyanates. The diisocyanates according to the invention constitute a new class of stable diisocyanates which have a substantially lower vapor pressure than the simple diisocyanates used for their preparation.
Although it was already known from J. Organomet. Chem., 169 (1979), 171-184 that trialkylsilylcyanides react with organic monoisocyanates to form imidazolidine diones, it could not be concluded from this prior publication, which deals exclusively with the reaction between monoisocyanates and trialkylsilylcyanides, that the diisocyanates according to the invention would be obtainable by the process according to the invention.